title: Water-soluble gold nanoparticles protected by fluorinated amphiphilic thiolates.
abstract: The preparation and the properties of gold nanoparticles (Au NPs) protected by perfluorinated amphiphiles are described. The thiols were devised to form a perfluorinated region close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water. The monolayer protected clusters were prepared, in an homogeneous phase using sodium thiolates because of the low nucleophilicity of the alpha-perfluorinated thiols, and fully characterized with (1)H, (19)F NMR spectrometry, IR and UV-vis absorption spectroscopies, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Au NPs with core diameters ranging from 1.6 to 2.9 nm, depending on the reaction conditions, were obtained. Water-soluble NPs (MPC-F8-PEGs) were obtained with the thiol HS-F8-PEG ending with a short poly(ethylene glycol) unit (PEG-OMe 550), whereas thiols with shorter PEG chains give rise to NPs insoluble in water. MPC-F8-PEGs undergo an exchange reaction with amphiphilic alkyl thiols. ESR investigations, using a hydrophobic radical probe, indicate that the MPC-F8-PEG monolayer shows a greater hydrophobicity compared to the analogous hydrogenated monolayer.
authors.affiliation: Department of Chemical Sciences and INSTM, Trieste Unit, University of Trieste, via L. Giorgieri 1, I-34127 Trieste, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gentilini
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Evangelista
authors.forename: Petra
authors.initials: P
authors.lastname: Rudolf
authors.forename: Paola
authors.initials: P
authors.lastname: Franchi
authors.forename: Marco
authors.initials: M
authors.lastname: Lucarini
authors.forename: Lucia
authors.initials: L
authors.lastname: Pasquato
mesh_terms: D017611:Fluorine Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D053768:Metal Nanoparticles / Q000737:chemistry*; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D012995:Solubility; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D017611:Fluorine Compounds; D013438:Sulfhydryl Compounds; D014867:Water; D009569:Nitric Oxide; D011092:Polyethylene Glycols; D006046:Gold